The present invention relates to a flame-retardant nylon polymer moulding composition, hereinafter referred to as a nylon resin composition which exhibits a good stability when it is in a molten state. More particularly, it is concerned with a flame-retardant nylon resin composition which, owing to its good stability in a molten state, resists heat encountered during soldering and does not suffer decomposition and degradation during melt molding.
A nylon improves in heat resistance as its melting point rises. On the other hand, a nylon with a high melting point needs a high processing temperature which causes decomposition and degradation during melt-molding, giving rise to molded items having a poor appearance.
Thus, it is difficult to obtain both a high heat resistance and ease of processing. We can attempt to overcome these difficulties, various compositions have been proposed which contain a polyamide copolymer and a flame retardant.
It is known that a polyamide copolymer having good heat resistance and moldability is obtained by copolymerizing hexamethylene terephthalamide and hexamethylene adipamide or by copolymerizing hexamethylene terephthalamide and caproamide (see JP-A-206827/1985, JP-A-159422/1986, and JP-A-283653/1986). Nylon resin compositions used in the electric and electronic industries are required to meet the UL-94 standard for a high degree of flame retardance (established by the Underwriters Laboratories in the U.S.). To this end, a variety of halogen-based flame-retardants have been proposed. It is known to incorporate, in a polyamide a brominated polystyrene as a flame-retardant and additionally a metal oxide as an auxiliary flame-retardant. (see JP-A-47044/1976 and JP-A-1403/1976). In addition, JP-A-116054/1979 discloses a composition composed of nylon and a brominated polyphenylene ether and attempts to improve this composition by incorporation of further additives are disclosed JP-A-23260/1987 and JP-A-138264/1989.